TIMING BELT

OK I took my truck in to have timing belt replaced and ever since the check engine light has been coming on. Shop would not stand behind it they said they did nothing wrong. I took to Toyota dealership and they found the harmonic balancer pulley was removed and not put back on correctly causing scoring to the crankshaft and timing to be off. They have also told me that the head gasket needs replaced. Could that be from the timing belt being done incorrectly?

I have a few problems with what this dealers work shops is reporting, firstly if the harmonic balancer is loose you can damage the key way but more often than not the harmonic balanced is flogged out and the crank is fine, this WILL not affect the timing in any manner what so ever. A problem with the timing belt installation will not affect the head gasket directly, other problems more evident will be in place for this to occur.